1.23.toString();//'1.23'
typeof 1.23.toString(); //string
NaN.toString();//'NaN'
Infinity.toString();//'Infinity'
-1.23.toString(); // -1.23
typeof -1.23.toString() // number

// 整数
0.toString() // 错误的写法
(0).toString() // 0

console.log(1.23.toString())
console.log(typeof 1.23.toString())
console.log(NaN.toString())
console.log(Infinity.toString())
console.log(-1.23.toString())
console.log(typeof -1.23.toString())
